Conventionally, for a variety of electronic devices including mobile phones, gaming machines and digital cameras, a mechanical switch, such as a tact switch or a membrane switch, is used in general as an input apparatus allowing an operator to perform input operations. These days, small terminal devices are often equipped with various functions, and such terminal devices have keys and buttons constituted by various switches on a body surface thereof.
In general, such a switch is assigned one operation (or one program). For example, the mobile phone outputs a number corresponding to the key upon detection of a pressing input to a numerical keypad and displays a menu panel upon detection of the pressing input to a menu key.
However, if an operator carries out a plurality of operations in series with each of different switches assigned respective operations, it may result in a substantially troublesome task. It may be considered to set such that a plurality of operations are sequentially carried out with a single switch every time an input to the switch is detected, such an input method requires predefinition of an order of the operations. Therefore, an operation of immediate execution of arbitrary operations desired by the operator is not enabled.
In order to address such a problem described above, there has been suggested an input apparatus with a plurality of operations assigned to an input mode to one switch (for example, see Patent Document 1).
The input apparatus described in Patent Document 1 can receive inputs at two levels in accordance with operation force (a pressure load) applied by the input operation.
FIG. 8 is a cross-sectional view schematically illustrating an internal configuration of an operation apparatus 100 described in Patent Document 1. As illustrated in FIG. 8, the operation apparatus 100 has a first detection means 200 and a second detection means 300, both of which are constituted by the membrane switch. The second detection means 300 is arranged under (in a pressing direction) the first detection means 200. A portion to be in direct contact with a finger F of the operator is made of a flexible member, which bends when the operator presses the operation apparatus 100 and thereby conveys the pressure to the first detection means 200. When the operator presses down a position corresponding to a first contact point S3 applying a light weight (first operation force) with the finger F, a first upper conductive portion 201c and a first lower conductive portion 202c come into contact with each other, and thereby the first contact point S3 is conducted. This is defined as a first level input. Further, when the finger F presses down applying a heavier weight (second operation force), a second upper conductive portion 301c and a second lower conductive portion 302c come into contact with each other, and thereby a second contact point T3 is conducted. This is defined as a second level input. FIG. 8 illustrates a state that not only the first contact point S3 detects the first level input but also the second contact point T3 detects the second level input as the operator's finger F presses the operation apparatus 100 applies the second operation force.
Since the input apparatus described above receives inputs at two levels in accordance with the pressure of the operator's input, different operation may be assigned to each of the levels. With such an input apparatus, the operator can separately carry out a plurality of inputs by adjusting a pressure of one pressing input to one switch (input apparatus).
That is, the input apparatus for receiving inputs at two levels enables the operator to carry out the first level input by maintaining light pressure on the button. This input state is called “halfway pressing”, and referred to as the “first level input” hereinafter. This input apparatus also enables the operator to carry out the second level input by pressing the button with pressure heavier than that of the first level input. This input state is called “full pressing”, and referred to as the “second level input” hereinafter.
As an example of typical usages of the input apparatus for receiving the inputs at two levels in accordance with the pressure by such a mechanical switch, there is a shutter button of a camera. In general, for the mobile phones and the like having a digital camera function, the “halfway pressing” for the first level input by the operator turns on functions for adjusting AE (Auto Exposure) or for adjusting AF (Auto Focus). If the operator carries out the “full pressing” for the second level input in this state, the shutter is released. As described above, it is possible to assign different operations to the first level input and the second level input and, in addition, the operator can separately operate the different operations as desired.
It is to be noted that the input apparatus for receiving inputs of a plurality of levels in accordance with the pressure is not limited to the mechanical switch. For example, there is suggested an input apparatus of a touch panel type, composed of a combination of a display unit and a position input device, for receiving inputs of a plurality of levels in accordance with the pressure by software processing (for example, see Patent Document 2).
The input apparatus of the touch panel type described in Patent Document 2 has a position detection means for detecting a position of a pressing operation on the touch panel provided on a surface portion of a displayed screen and a pressure detection means for detecting a pressure applied on the touch panel. This input apparatus enables inputs of two systems in one pressing operation to the touch panel: an input in accordance with a position detected by the position detection means and multi-level inputs in accordance with the pressure detected by the pressure detection means.
This input apparatus allows the operator to simultaneously carry out an input of a first system in accordance with a position of the pressing operation and an input of a second system in accordance with a pressure on the touch panel, in pressing operation to the touch panel on the displayed screen. At this time, selection is enabled on multiple levels, i.e., three or more levels, in accordance with the pressure on the touch panel. Accordingly, the operator can carry out the input of the two systems in one pressing operation to the touch panel, which enables reduction in the number of pressing operations.
As stated above, both of the input apparatus using the mechanical switch and the input apparatus using the touch panel can receive inputs of a plurality of levels in accordance with the pressure. Since those input apparatuses receive the input classifying into a plurality of levels in accordance with the pressure, a plurality of functions are collected to one button or key. Thereby, it is possible to reduce the number of keys and buttons serving for input operations. Especially for small terminals such as the mobile terminals, there is a difficulty in arranging numerous keys and buttons on their bodies due to their housings in small sizes. Accordingly, if the mobile terminal can separately perform a plurality of functions with a small number of keys and buttons, the number of keys and buttons to be provided on the terminal body is advantageously reduced.